Aerosol dispensers are well known in the art. Aerosol dispensers typically comprise an outer container which acts as a frame for the remaining components and as a pressure vessel for propellant and product contained therein. Outer containers made of metal are well known in the art. However, metal containers can be undesirable due to high cost and limited recyclability. Attempts to use plastic have occurred in the art. Relevant attempts in the art to employ plastic in aerosol dispensers are found in U.S. Pat. Nos. 2,863,699; 3,333,743 and 2009/0014679.
The outer containers are typically, but not necessarily, cylindrical. The outer container may comprise a bottom for resting on horizontal surfaces such as shelves, countertops, tables etc. The bottom of the outer container may comprise a re-entrant portion as shown in U.S. Pat. No. 3,403,804. Sidewalls defining the shape of the outer container extend upwardly from the bottom to an open top.
The open top defines a neck for receiving additional components of the aerosol dispenser. The industry has generally settled upon a neck diameter of 2.54 cm, for standardization of components among various manufacturers, although smaller diameters, such as 20 mm, are also used. Various neck shapes are shown in US 2007/02782531 A1; U.S. Pat. Nos. 7,303,087; 7,028,866; and commonly assigned U.S. Pat. No. 6,019,252.
Typically a valve cup is inserted into the neck. The valve cup is sealed against the neck to prevent the escape of the propellant and loss of pressurization. The valve cup holds the valve components which are movable in relationship to the balance of the aerosol dispenser.
Aerosol dispensers, having a valve cup and movable valve components, may comprise different embodiments for holding, storing, and dispensing product used by the consumer. In one embodiment, the product and propellant are intermixed. When the user actuates the valve, the product and propellant are dispensed together. This embodiment may utilize a dip tube. The dip tube takes the product and propellant mixture from the bottom of the outer container. By dispensing from the bottom of the outer container, the user is more likely to achieve dispensing of the product/propellant mixture and not dispense pure propellant from the headspace. This embodiment may be used, for example, to dispense shaving cream foams.
The dip tube embodiment of an aerosol dispenser has the disadvantage that when the user tips the aerosol dispenser from a vertical orientation, dispensing of gas from the headspace, rather than dispensing of product/propellant mixture, may occur. This disadvantage may occur when the aerosol dispenser contains a product such as a body spray, which the user dispenses all over his/her body, often from inverted positions.
To overcome this disadvantage, other embodiments could be utilized. For example, a collapsible, flexible bag may be sealed to the opening on the underside of the valve cup or may be placed between the valve cup and the container. This bag limits or even prevents intermixing of the contents of the bag and the components outside of the bag. Thus, product may be contained in the bag. Propellant may be disposed between the outside of the bag and the inside of the outer container. Upon actuation of the valve, a flow path out of the bag is created. Gage pressure from the propellant disposed between the bag and the outer container causes pressurization of the product, forcing the product to flow into ambient pressure. This embodiment is commonly called a bag on valve and may be used, for example, in dispensing shaving cream gels. In either embodiment, flow to the ambient may comprise droplets, as used for air fresheners or may comprise deposition on a target surface, as may occur with cleansers. An aerosol container having a bag therein may be made from a plural layer preform, provided both layers consist of or consist essentially of the same recycling stream. A plural layer preform may have plural layers disposed one inside the other, and particularly two layers as occurs in a dual layer preform. These layers may be generally coextensive and congruent. Relevant attempts in the preform art include US, 2010/0330313 A1, 2010/0239799 A1, 2008/0257846 A1, 2012/0187067 A1, 2012/0132607 A1, 2011/0024450 A1, 2008/0257883 A1, 2010/252583 A1, 6254820, WO 9108099 and. Other attempts in the dual layer bottle art do not use preforms, and therefore have the disadvantage of more expensive and complex manufacture. Such attempts include U.S. Pat. Nos. 3,450,254, 4,330,066, 2011/0248035 A1.
Problems with plastic aerosol containers have been longstanding. For example reported bursting of plastic aerosol containers reached back to 1959. See, M. Johnsen, Ph.D., The Elusive Plastic Aerosol Part 1, SPRAY TECHNOLOGY & MARKETING, April, 2009, page 20. DOT regulations of aerosols also date back to the 1950's. Id. 1952. Exemptions were granted in 2005-2006, but only relating to certain plastic aerosols. See, M. Johnsen, Ph.D., The Elusive Plastic Aerosol Part 2, SPRAY TECHNOLOGY & MARKETING, June, 2009, pages 18-19.
One material judged suitable for a plastic aerosl is PET, which has been used for more than 30 years. Id at 17. PET is typically less expensive than PEN, but has greater permeability. Id. at 18. To overcome the permeability problem, one of skill may select a hydrocarbon propellant, as it is reported to not permeate PET. Id., The Elusive Plastic Aerosol Part 1, SPRAY TECHNOLOGY & MARKETING, April, 2009, page 22.
Once the aerosol dispenser is manufactured, shipped to retail, sold to and used by the consumer, the product in the aerosol dispenser is eventually depleted. Upon depletion, the aerosol dispenser is typically discarded. Being discarded increases landfill and fails to recycle potentially usable materials. Recycling presents an opportunity to reduce landfill, conserve energy and reuse raw materials in another aerosol dispenser or in other products. But recycling presents its own challenges.
For example, fires at recycling plants have been reported. E.g. fires have been reported to have occurred as far back as 2007 at a recycling warehouse in Dayton, Ohio and as recently as 2013 at a 4,000 ton per day plant in New Jersey.
Yet other recycling problems include separation of various material from a consumer package goods, such as an aerosol dispenser, into reusable material steams. The Society of the Plastics Industry [SPI] has developed a widely used resin identification system. The SPI system divides resins into seven classes, as set forth in below. The listing below shows each class of polymer has different melting temperatures [Tm, degrees C.], glass transition temperatures [Tg, degrees C.] and Young's moduli [YM, GPa].

Polyethylene Terephthalate (PET, PETE)
Clarity, strength, toughness, barrier to gas and moisture.
Soft drink, water and salad dressing bottles; peanut butter and jam jars
Tm=250; Tg=76
YM=2-2.7

High-Density Polyethylene (HDPE)
Stiffness, strength, toughness, resistance to moisture, permeability to gas.
Water pipes, hula hoop rings, five gallon buckets, milk, juice and water bottles; grocery bags, some shampoo/toiletry bottles
Tm=130; Tg=−125
YM=0.8

Polyvinyl Chloride (PVC)
Versatility, ease of blending, strength, toughness.
Blister packaging for non-food items; cling films for non-food use. Not used for food packaging as the plasticisers needed to make natively rigid PVC flexible are usually toxic. Non-packaging uses are electrical cable insulation; rigid piping; vinyl records.
Tm=240; Tg=85
YM=2.4-4.1

Low-Density Polyethylene (LDPE)
Ease of processing, strength, toughness, flexibility, ease of sealing, barrier to moisture. Frozen food bags; squeezable bottles, e.g. honey, mustard; cling films; flexible container lids.
Tm=120; Tg=−125

Polypropylene (PP)
Strength, toughness, resistance to heat, chemicals, grease and oil, versatile, barrier to moisture. Reusable microwaveable ware; kitchenware; yogurt containers; margarine tubs; microwaveable disposable take-away containers; disposable cups; plates.
Tm=173; Tg=−10
YM=1.5-2

Polystyrene (PS)
Versatility, clarity, easily formed
Egg cartons; packing peanuts; disposable cups, plates, trays and cutlery; disposable take-away containers;
Tm=240 (only isotactic); Tg=100 (atactic and isotactic)
YM=3-3.5

Other (often polycarbonate or ABS)
Dependent on polymers or combination of polymers
Beverage bottles; baby milk bottles. Non-packaging uses for polycarbonate: compact discs; “unbreakable” glazing; electronic apparatus housings; lenses including sunglasses, prescription glasses, automotive headlamps, riot shields, instrument panels;
Polycarbonate: Tg=145; Tm=225
Polycarbonate: YM=2.6; ABS plastics: YM=2.3
As such, it is reported that separation of the recycled materials into different classes must be efficient, because even small amounts of the wrong time of resin can be detrimental to the recycling mix. http://en.wikipedia.org/wiki/Resin_identification_code.
Complicating the matter, not all classes of materials are recycled in every community. Confusion can occur as to which materials can be recycled and which material cannot be recycled.
Further complicating the matter are various regulations governing manufacture and transportation of aerosol dispensers. Not all configurations which might be recycled are feasible to make or sell. The problem becomes even more complicated.
Further complicating the matter are the commonly used techniques for separating materials into various recycling streams, typically floating/sinking in liquid or IR separation. These techniques may be ineffective for small parts, as often found in an aerosol container or for parts which are chemically bonded together.
Accordingly, plastic aerosol containers must be constructed to meet the longstanding aerosol needs and to be conveniently recyclable. Such construction must go beyond the outer container which typically is the component having the largest single gram weight. Such construction must further consider the minor components and even the propellant. Accordingly, a new approach is needed.